The present invention relates to a multidirectional switch and an operation unit containing the switch, wherein a suitable application sector of the operation unit includes a control unit for an automobile air-conditioner or the like.
A conventional operation unit for controlling an air-conditioner of an automobile has a panel as shown in FIG. 10; where a number of push button switches 1 corresponding to respective functions are disposed within a frame 3, together with LED displays or the like indicating the functions. Lately, automobiles have been equipped with varieties of additional functions; and a so-called multidirectional switch, which is capable of handling varieties of instructions in a single-body switch, has been increasingly used in the operation units, instead of using a plurality of single-function push button switches 1.
Such a multidirectional switch of a conventional structure is described in the following with reference to FIG. 11 through FIG. 13.
FIG. 11 is a cross sectional side view of a conventional multidirectional switch, and FIG. 12 shows an exploded perspective view of the multidirectional switch.
As shown in FIG. 11 and FIG. 12, a cylindrical case 5 made of an insulating resin is provided with a boss 5A protruding upwardly from a center of a bottom surface of the case, and two protrusions 5B in the vicinity of the boss 5A.
A hole 5C in the boss 5A houses a supporting pin 7, which is pushed upwardly by a slightly compressed coil spring 6. An upper end of the supporting pin 7 has a spherical surface.
A wiring board 8 having a plurality of conductive patterns (not shown) on both of its surfaces is provided with five push button switches 9A-9E on its upper surface, which are disposed in a radial arrangement around a central through hole 8A and fixed thereon by soldering or the like, and perform electrical connection/disconnection in accordance with a pressing operating force accompanying a click feeling.
The wiring board 8 is fixed with two screw bolts 10 onto the protrusions 5B of case 5, with the through hole 8A penetrated by the boss 5A of case 5.
The wiring board 8 is coupled with lead wires 11 at one end by soldering, or by using a conductive adhesive, and the lead wires 11 are connected via a conductive pattern with respective push button switches 9A-9E.
The lead wires 11 extend from the case 5 through an opening 5D, to be electrically connected at another end with an electronic circuit (not shown) of an automobile.
A swaying body 12 made of an insulating resin is provided just above the wiring board 8. The swaying body 12 is provided with an operating axle 12B protruding upwardly from a center of an upper surface of a bowl part 12A.
Provided at a center of a lower surface of the bowl part 12A is a clicking void 12C, which has an elastic contact with the supporting pin 7 at the upper end thereof. The bowl part 12A is provided with five push sections 12D-12H extending in a radial arrangement from an outer circumference of the bowl part. Tip ends of the push sections make contact at their bottom surfaces with upper surfaces of the push button switches 9A-9E.
A cover 13 covering the case 5 from above is provided on its upper surface with varieties of markings, painted by a printing process or a similar method. An opening 13A is provided at a center of the cover 13, and a contact portion 13B of a spherical shape is provided at a lower part of the opening 13A.
The swaying body 12, which is pushed upwardly by the supporting pin 7, makes contact at the upper surface of the bowl part 12A with the contact portion 13B. Thus, the swaying body 12 is supported by the supporting pin 7 at its upper end, so that the swinging body can sway around the upper end of the supporting pin.
An operation body 14 has an operating area 14A of a flange shape at an upper surface of the operation body, and a coupling section 14B protruding downwardly from a center of a lower surface of the operation body. The coupling section 14B is inserted through the opening 13A of cover 13 to be coupled and fixed with the operating axle 12B of the swaying body 12. A conventional multidirectional switch is thus constituted.
In the above-configured multidirectional switch, when the operation body 14 is pressed in a certain specific direction, for example, when the operating area 14A is pressed downwardly at the left end the swaying body 12 sways to the left with the upper end of the supporting pin 7 serving a fulcrum point so that the bottom end surface of the push section 12D pushes the push-button switch 9A downwardly. Then, the push-button switch 9A is brought into an electrical connection.
At this time, as a result of swaying of the swaying body 12, the push sections 12E and 12H located next to the push section 12D also move slightly downwardly to press the push-button switches 9B and 9E located next to the push-button switch 9A. Since the loads of pressing the push-button switches 9B and 9E are added to that of pressing the push-button switch 9A, a click feeling of the push-button switch 9A itself is deteriorated.
However, as a result of the swaying motion of swaying body 12, the point of making contact between the upper end of the supporting pin 7 and the clicking void 12C shifts, which results in a change in the amount of flexion with the coil spring 6. This generates a click feeling corresponding to the amount of load drop P1 as exhibited in FIG. 13, which is an operational characteristics diagram.
In the conventional multidirectional switches of the above-described configuration, the coil spring 6 and the supporting pin 7 are the essential components for generating the click feeling; which means an increased number of constituent components. Furthermore, the click feeling of the push-button switch 9A itself, which makes electrical connection/disconnection in accordance with a pressing operation, is deteriorated, resulting in a reduced amount of the load drop P1. Thus, it has been difficult to provide a satisfactory operational feeling with the conventional multidirectional switches.
A multidirectional switch of the present invention has an operation body comprising a plurality of operating areas, each of which is positioned at a middle area between contact switches. A pressing force applied to the operation body sways a swaying body, bringing two contact switches into electrical connection/disconnection at substantially the same time. With the above-described structure, where push structure of the swaying body press two contact switches at substantially the same time, a superior feeling of operation is generated without requiring such constituent components as a coil spring, supporting pin or the like. Thus, the present invention provides an inexpensive multidirectional switch that is formed of fewer components, and provides a superior feeling of operation.